On-chip lidar switching failure monitoring

Abstract

Disclosed are systems for monitoring on-chip LiDAR switching failure. A reduced number of power monitors are implemented between the switch fabric and transmit / receive pixels to capture the scan pattern thereby determining an operational status of the switches of the switch fabric.

Description

ON-CHIP LIDAR SWITCHING FAILURE MONITORINGFIELD OF THE INVENTION

[0001] The present disclosure relates to on-chip LiDAR (Light Detection and Ranging) systems, and particularly to on-chip LiDAR switching failure monitoring.BRIEF SUMMARY

[0002] According to a first broad aspect there is provided an integrated photonics system including: a plurality of pixels for launching and receiving optical signals into and from free-space; one or more switch fabrics coupled to said pixels and comprising a network of switches coupled via waveguides; at least one LiDAR transceiver coupled to the one or more switch fabrics for providing and receiving said optical signals from the plurality of pixels via the one or more switch fabrics; a plurality of power monitors optically coupled between the switch fabric and respective adjacent pixels; and processing circuitry configured for receiving digital data indicative of the power measured by the power monitors, for identifying a switching pattern of the one or more switch fabrics with use of the digital data and for determining a functionality of the one or more switch fabrics from the identified pattern.

[0003] In some embodiments, each power monitor of the plurality of power monitors comprises an optical tap for tapping a portion of the optical signal destined for the respective adjacent pixel, and a photodiode for converting the portion of the optical signal into an analog electrical signal.

[0004] In some embodiments, the plurality of power monitors are coupled to a plurality of receivers for converting the analog electrical signals into the digital data.

[0005] In some embodiments, the number of power monitors is less than the number of pixels.

[0006] In some embodiments, the number of receivers is less than the number of power monitors.

[0007] In some embodiments, the one or more switch fabrics comprises a plurality of switch fabrics driven by the same driving signals, and multiple coordinate power monitors are coupled to the same receiver.

[0008] In some embodiments, the number of power monitors is half the number of pixels, a power monitor coupled between each switch of a last level of a switch fabric of the one or more switch fabrics and one of the pixels the switch is coupled to.

[0009] In some embodiments, the processing circuitry is further configured for receiving reference digital data from the receivers indicative of a normal pattern of operation for the switch fabric, storing the reference digital data, and comparing the reference digital data with digital data received from the receivers for determining the functionality of the one or more switch fabrics.

[0010] In some embodiments, the processing circuitry is further configured for generating an alarm signal for indicating a failure of the one or more switch fabrics.

[0011] In some embodiments, each of the one or more switch fabrics couples optical signals to and from the pixels for use in detection and ranging.

[0012] In some embodiments, at least one of the switch fabrics of the one or more switch fabrics comprises a receive switch fabric and is coupled to pixels which are dedicated to receiving back-scattered LiDAR optical signals from free-space, and wherein the power measured by the power monitors includes a power of a test optical signal generated for monitoring a functionality of the receive switch fabric.

[0013] In some embodiments, the one or more switch fabrics comprises a receive switch fabric and a transmit switch fabric both coupled to the same pixels, each pixel for launching and receiving optical signals into and from free-space, wherein the receive switch fabric directs a test optical signal to a first set of the power monitors adjacent the receive switch fabric, the test optical signal generated for monitoring a functionality of the receive switch fabric, and wherein the transmit switch fabric directs optical signals to a second set of power monitors adjacent the transmit switch fabric, the second set of power monitors separate and distinct from the first set of power monitors.

[0014] Some embodiments further provide for a plurality of duplexers, one for each pixel, coupled to the pixel and to both the receive switch fabric and the transmit switch fabric, fortransmission of optical signals from the transmit switch fabric to the pixel and transmission of back-scattered optical signals from the pixel to the receive switch fabric, and wherein the power monitors tap the optical power of optical signals travelling between the receive and transmit switch fabrics and the duplexers.

[0015] The foregoing and additional aspects and embodiments of the present disclosure will be apparent to those of ordinary skill in the art in view of the detailed description of various embodiments and / or aspects, which is made with reference to the drawings, a brief description of which is provided next.BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The foregoing and other advantages of the disclosure will become apparent upon reading the following detailed description and upon reference to the drawings.

[0017] FIG. 1 is a schematic block diagram of a LiDAR system including failure monitoring according to an embodiment implemented using an architecture with a Tx / Rx switch fabric.

[0018] FIG. 2 is a schematic block diagram of an example arrangement of a laser and the LiDAR transceiver of the system of FIG. 1.

[0019] FIG. 3 illustrates a time-domain distribution of monitored optical power during normal operation of an example LiDAR system according to an embodiment.

[0020] FIG. 4 illustrates a time-domain distribution of monitored optical power after failure of Level 1 switches of an example LiDAR system according to an embodiment.

[0021] FIG. 5 illustrates a time-domain distribution of monitored optical power after failure of a Level 2 switch of an example LiDAR system according to tin embodiment.

[0022] FIG. 6 illustrates a time-domain distribution of monitored optical power after failure of a Level 3 switch of an example LiDAR system according to an embodiment.

[0023] FIG. 7 is a schematic block diagram of a LiDAR system including failure monitoring according to an embodiment implemented using an architecture with separate Tx and Rx switch fabrics.

[0024] FIG. 8 is a schematic block diagram of an example arrangement of a laser and the LiDAR transceiver of the system of FIG. 7.

[0025] While the present disclosure is susceptible to various modifications and alternative forms, specific embodiments or implementations have been shown by way of example in the drawings and will be described in detail herein. It should be understood, however, that the disclosure is not intended to be limited to the particular forms disclosed. Rather, the disclosure is to cover all modifications, equivalents, and alternatives falling within the scope of an invention as defined by the appended claims.DETAILED DESCRIPTION

[0026] Many LiDAR systems utilize multiple optical receive / transmit locations at the system boundary to direct, like an optical antenna, optical signals into free-space and to receive optical signals scattered back from objects and surroundings of interest. On-chip pixel locations directing optical signals into free-space may also operate to receive optical signals therefrom, and may be referred to as emitters or simply as pixels, each with a unique location and which may or may not have its own unique coupling direction. Although reciprocity is a general rule for typical optical systems, in some LiDAR systems, each pixel is dedicated to either launching LiDAR optical signals into free space or to receiving scattered signals only. In some implementations, the pixels are arranged in an array.

[0027] Some chip-based LiDAR systems employ one or more on-chip LiDAR transceivers which launch and detect optical signals for the system. In LiDAR systems implementing beam scanning, typically a controllable switch fabric is implemented between each of the one or more LiDAR transceivers and multiple pixels, to switch the optical signals to and receive optical signals from different pixels at different locations in some sequence. Typically, at any one time, each one of the one or more on-chip transceivers is optically coupled via a switch fabric to one pixel, for receiving optical signals or transmitting optical signals or both. Operation of the switch fabric in this manner enables each pixel to function as an addressable pixel. Some multiple transceiver LiDAR systems employing beam steering employ multiple LiDAR transceivers and switch fabrics to address multiple respective pixels in a parallel fashion. In such implementations the switch fabrics are driven by the same global drive signals to simultaneously and in a parallel fashion address pixels for each transceiver at various respective locations simultaneously, for example, by section or row.

[0028] In some embodiments, each LiDAR transceiver sends light out via the switch fabric and then receives the back-scattered signal from the same switch fabric, determining primarily, but not limited to, an object’s distance, reflectance, and velocity. In some embodiments, a LiDAR transceiver may transmit and receive optical signals through different switch fabrics and pixels, in some cases, the switch fabrics and pixels are dedicated to only receive or transmit optical signals. In some embodiments, a LiDAR transceiver may transmit and receive optical signals through different switch fabrics but through the same pixels. In some cases, the different switch fabrics are dedicated to only receive or transmit optical signals. Some of the types of LiDAR transceiver contemplated by the embodiments include time-of-flight LiDAR transceivers, amplitude modulation coded LiDAR transceivers, and Frequency-Modulated-Continuous-Wave (FMCW) LiDAR transceivers.

[0029] LiDAR systems with strict functional safety requirements are typical for applications such as autonomous vehicles and robotics. According to those requirements or standards, the system needs to guarantee the fidelity of the data such that the point-cloud it produces has data points which are spatially accurate. Consequently, the system should be able to detect early signs of drifts, systematic or other error, and apply correction quickly (as defined by the requirements) as well as to determine and signal failure of functionality to prevent misinforming the overall system relying upon the data.

[0030] One naive way to guarantee functional safety would be to independently monitor light emitted and received at the locations of all available pixels. Such an approach can quickly become overwhelming or impractical for the system as the number of pixels increases, and particularly if the number of power monitor and receiver pairs scale one-to-one with the number of pixels. Another naive way to guarantee functional safety would be to independently monitor every switch of all the switch fabrics, which may require additional integrated circuitry to ensure the switch is functioning properly in response to control signaling, increasing complexity, power usage, manufacturing costs and on-chip real-estate usage.

[0031] To save power, and to reduce manufacturing costs and the usage of on-chip real- estate, embodiments disclosed herein provide alternatives to monitoring optical signals at every individual switch or pixel location, and in some cases utilize a much smaller number of power monitors and receivers than the total number of pixels or switches. Since the controllable switch fabric utilized for beam scanning connects every intended pixel to the appropriate one or moretransceivers and since the switches of the switch fabric constitute the last points of failure before the pixels themselves, embodiments disclosed herein can effectively monitor the functional status of the system by monitoring optical signals traversing the switch fabric prior to egress at the pixels. Embodiments analyze the optical signals emerging from the switching fabric to assess the switching pattern of the switch fabric to determine a functioning thereof. Since the switch fabric operates with a pre-defined scan pattern for the pixels, which in some cases is reused in a parallel fashion across multiple respective switch fabrics, embodiments herein utilize only a relatively small number of receivers to detect any changes in this scan pattern. Consequently, embodiments disclosed herein provide for on-chip LiDAR system monitoring that can identify promptly any failure of beam scanning utilizing relatively fewer power monitors and receivers than required by naive or brute force approaches.

[0032] According to the embodiments, several power monitors, equal to or less than the number of pixels, are placed after the switch fabric and just before the pixels to monitor the power changes in the transmit path. Each power monitor comprises a small power ratio photonics tap, typically in the order of 0.1% to 5%, and a photodetector that is placed right after the tap.

[0033] For applications of the highest levels of safety, one power monitor should be placed before one or the other of the pixels that connects to any switch in the last switch level in the switch fabric. In embodiments such as that depicted in FIG. 1 each LiDAR transceiver connects to the addressed pixels one at a time with a global scan pattern that applies to all switch fabrics uniformly. In some embodiments the photocurrent signals generated from the power monitors of the simultaneously addressed pixels across all switch fabrics and LiDAR transceivers which are common are combined and fed into a common electronics receiver that may include, but is not limited to, a transimpedance amplifier (TIA) and an analog-to-digital converter (ADC).

[0034] Each of the received photocurrent signals is monitored in real time to check for any pattern changes. Initially, during a calibration step, the system obtains a reference signal waveform that indicates a normal operation for the switch fabric. Any deviation from the reference waveform will alarm the system (or the user) of a wrong scan pattern that would yield false results.

[0035] With reference to FIG. 1, a LiDAR system 1000 including failure monitoring according to an embodiment implemented using an architecture with a Tx / Rx switch fabric 1200 will now be discussed.

[0036] A first and a second LiD AR transceiver 1051 1052 address 16 pixels 1450 (PX1, PX16 such as 1451) through a Tx / Rx switch fabric 1200 including switches (such as 1211) arranged in two 1:8 switch trees. The switch trees are binary and arranged into three levels, Level1, LI 1210 optically coupled (via waveguides such as 1205) to the transceivers 1051 1052, Level2, L2 1220, coupled to Level 1, and Level 3, L3 1230 coupled to Level 2. The Level 3 switches are the last switches in the switch fabric 1200 and are optically coupled to the pixels 1450. Optical signals 1455 traverse the pixels 1450 into free-space and back-scattered optical signals are received by the pixels 1450. Between the Level 3 switches and the pixels are coupled a group of power monitors 1400, each one coupled along at least one waveguide between each Level 3 switch and one of its coupled pixels 1450, such as power monitor 1410. In the embodiment of FIG. 1, there is a power monitor 1400 connected between the switch fabric and every other pixel 1450. Each power monitor includes a photonics tap 1412, coupled by a short waveguide 1414 to a photodiode 1416. The photodiode 1416 is coupled via an electrical connection to a receiver such as RX1 1610. In the embodiment depicted in FIG. 1, each switch tree is driven by the same control signaling, such that during normal operation power monitors 1400 of the first tree are expected to detect identical signals as coordinate power monitors 1400 of the second tree. Consequently, coordinate power monitors 1450 are together coupled to the same receiver RX 1 , ... , RX4 1610, ... 1640. The receivers are coupled to one or more processors 1080.

[0037] The two LiD AR transceivers 1051 1052 transmit and receive optical signals over waveguides 1205 traversing the switches 1211 in each level 1210 1220 1230 of the switch fabric 1200. The individual switches, controlled by control signaling (not illustrated) assert with a defined scan pattern, the coupling of the optical paths within the switch fabrics such that the pixels 1450 are connected to the transceivers one at a time as shown in FIG. 3. Each pixel 1450 in turn transmits and receives optical signals 1455 to and from the environment. Each power monitor 1400 taps a portion of the optical power from the switch fabric 1200 destined for the pixel 1440 it is situated proximate to using the photonics tap 1412 of the power monitor 1400. In some embodiments, the level of power tapped is on the order of 0.1% to 5%. The tapped optical signal traverses the short waveguide 1414 of the power monitor 1400 to the photodiode 1416 (or any other suitable optical detector) which converts the optical signal into an electrical signal. The electrical signal produced by the power monitor 1440 proceeds via the electrical connection 1470 to a receiver e.g. RX1 1610 which in some embodiments includes a TIA and ADC. As notedabove, coordinate signals from multiple switch trees are combined i.e. output to the same receiver 1610. Outputs from the receivers are provided to the one or more processors 1080 which analyzes the patterns produced, in some embodiments, comparing the patterns with a reference pattern corresponding to normal operation.

[0038] It should be noted that in the embodiment illustrated in FIG. 1, pixels at positions adjacent the upper switch tree are connected to the respective upper transceiver at the same time as pixels at coordinate positions adjacent the lower switch tree. For example pixel PX1 and pixel PX9 (and other coordinate pairs) will be connected to their respective transceivers both simultaneously and periodically. In addition, each power monitor that connects to coordinate pixel pairs are connected to the same receiver. For example, the power monitor adjacent pixel PX5 and the power monitor adjacent pixel PX13 are both coupled electrically to receiver RX3 1630.

[0039] Although the LiDAR system 1000 of FIG. 1 is shown including a switch fabric 1200 including two 1:8 switch trees, typically in a real photonics chip, there can be multiple copies of such systems that enable more pixels through even more LiDAR transceivers in parallel. In such cases, more than a pair of power monitors 1400 may be coupled electrically to a single receiver RX. Although the illustrated embodiment depicted in FIG. 1 is shown as implementing 1:8 binary switch trees, it should be understood that the power monitoring techniques and structures of the present disclosure are applicable to any kind of switch tree structure of a working LiDAR system.

[0040] With reference to FIG. 2, an example arrangement 2000 of a laser and LiDAR transceiver of the system of FIG. 1 will now be discussed.

[0041] A laser 2001 generates an original optical signal for use by the LiDAR system, and provides it to the LiDAR transceiver 2051. A duplexer 2022 of the LiDAR transceiver 2051 receives the original optical signal and splits it, sending one portion to the switch fabric and the remaining portion to a detector 2020 of the LiDAR transceiver 2051. The duplexer 2022 also receives back-scattered optical signals from the switch fabric, a portion of which is provided to the detector 2020. The detector compares and processes the portion of the original optical signal and the portion of the back-scattered optical signals to perform the detection and ranging of the LiDAR system.

[0042] With reference to FIG. 3, a time-domain distribution of optical power 3000 during normal operation of an example LiDAR system according to an embodiment will now bediscussed. It should be noted that the signals SI, ..., S8 correspond to the signals expected to be measured by power monitors, if present adjacent all pixels PX1, ..., PX8, and equally correspond to power signals that would be measured adjacent coordinate pixels PX9, ..., PX16. It should be noted, that in an embodiment such as that illustrated in FIG. 1, only SI, S3, S5, and S7 would actually be measured, and moreover, as part of an average (and up to a normalization factor, equivalent to the sum) of coordinate pixel pairs (PX1 and PX9, ..., PX8 and PX16).

[0043] The transmission is high for a particular pixel when the transceiver successfully connects. In normal operation, the pixels are connected one after another from pixels PX1 to PX8 (and simultaneously PX9 to PX16) then jumping back to PX1 (and PX9) again and the whole process repeats. Therefore, the receivers RX are effectively detecting predictable pulse trains to monitor the overall health of the switch fabric.

[0044] An abnormal switching behavior is detected if any of the signals generated by the receivers constitutes a pattern change. This pattern change could be a change in, but not limited to, the periodicities, heights, duty cycles, and timing of the pulses. Each type of change (or combination of the types) detected indicates a specific failure mode which can be analyzed and determined by the processor 1080. For example, FIG. 4 shows the case when all the Level 1 switches failed (upper tree) and the transmission going into the two outputs of each switch are identical at 0.5 (instead of switching between 0 and 1). In this case, all pixels have half the pulse height, and pixels PX4 and PX8 have longer pulse durations. This is a clear pattern change that may easily be detected.

[0045] In the example illustrated in FIG. 5, where the upper Level 2 switch failed (upper tree), it affects pixels PX1 to PX4 but not PX5 to PX8. However, the power monitor patterns for pixels PX1 to PX4 also changed quite differently.

[0046] In the last example illustrated in FIG. 6, where the second Level 3 switch failed (upper tree), it only affects pixels PX3 and PX4 but not the rest of the pixels.

[0047] It should be noted that monitoring only one of the neighboring pixels that shares the same switch on the last level is required, since one of these two pixels should detect the same changes or failures of switching at any switch level.

[0048] A LiDAR system 7000 including failure monitoring according to an embodiment implemented using an architecture with separate Tx and Rx switch fabrics 7200 7300 is structured similarly to that depicted in FIG. 1 except for the following differences. The Tx switch fabric7300 is coupled to an output only of the LiDAR transceiver 7051 , and hence it, and all of the pixels it couples to are devoted to transmission only. The Rx switch fabric 7200 carries both received back-scattered optical signals 7206 (dotted lines) as well as relatively low power test optical signals 7207 (solid line) on its waveguides 7205. The test optical signals generated by the LiDAR transceiver 7051 are utilized for testing the switch fabric 7200 which otherwise would not be possible. Unlike the embodiment depicted in FIG. 1 , during normal operation the expected power to be measured at the power monitors 7400 of the upper tree does not match those of the lower tree and hence, coordinate power monitor outputs from the two switch fabrics 7200 7300 are not combined and provided to common receivers RX. It is to be noted however, that LiDAR systems with multiple transceivers 7051 and multiple separate Tx and Rx switch fabrics 72007300 may be run in parallel, in which case coordinate power monitoring outputs from the same type of switch fabric may be combined and provided to common receivers RX.

[0049] FIG. 8 depicts an example arrangement 8000 of a laser and LiDAR transceiver of the system of FIG. 7. A laser 8001 generates an original optical signal for use by the LiDAR system, and provides it to the LiDAR transceiver 8051. A power splitter 8022 of the LiDAR transceiver 8051 receives the original optical signal and splits it, sending one portion to the Tx switch fabric and the remaining portion to a first switch 8024 of the LiDAR transceiver 8051. The power splitter 8022 may be a variable power splitter which allows control of how much power proceeds to the Tx switch fabric and how much power proceeds to the switch 8024. The switch 8024 outputs the remaining portion of the original optical signal to the detector 8020, or a second switch 8026. The second switch 8026 provides the remaining portion of the original optical signal to the Rx switch fabric for monitoring. The second switch 8026 also receives back-scattered optical signals from the Rx switch fabric which it forwards to a detector 8020. In some embodiments, one or more of the switches 8024 8026 are variable analog switches which can be controlled to direct to either port anywhere between 0% and 100% of the optical power. In some embodiments, one or more of the switches 8024 8026 output a fixed-ratio of power over its ports, and may comprise fixed-ratio splitters. The detector 8020 compares and processes the portion of the original optical signal and the back-scattered optical signals to perform the detection and ranging of the LiDAR system. The switches 8024 8026 however have the advantage of diverting all the power over in a very short period of time (that does not affect real operation) to give the power monitors much better SNR, for example during a short time period devoted to monitoring.

[0050] It also should be noted that in an alternative embodiment similar to that of FIG. 7, if the switches 8024 and 8026 and power splitter 8022 are controlled to match the expected powers measured on both the upper and lower trees over a short monitoring duration, coordinate power monitor outputs from the two switch fabrics 72007300 may be combined and provided to common receivers RX.

[0051] A LiDAR system 9000 including failure monitoring according to an embodiment implemented using an architecture with separate Tx and Rx switch fabrics 9200 9300 is structured similarly to that depicted in FIG. 7 except for the following differences. The Tx switch fabric 9300 coupled to an output only of the LiDAR transceiver 9051, and hence it is devoted to transmission only, however, it is coupled to the same pixels 9450 the Rx switch fabric is coupled to. As such, the pixels 9450 are utilized for both launching LiDAR optical signals into free-space and receiving back-scattered optical signals from free-space. Additionally, between the pixels 9450 and the power monitors 9400 a group of duplexers 9440 DPX1, ..., DPX8 are provided. In the embodiment of FIG. 9 placement of the duplexers 9440 helps to improve optical performance, avoid loss, and allow the separate switch fabrics each to deal with a single optical mode. In some embodiments, each duplexer 9440 has a single input / output port coupled to its adjacent pixel, a single output port coupled to the Rx switch fabric 9200, and a single input port coupled to the Tx switch fabric 9300. In some embodiments each duplexer 9440 is configured to allow nonobstructed transmission both for the intended Tx signal (from the Tx switch tree) from the input port to the input / output port, and for the intended back-scattered signal (from the adjacent pixel) from the input / output port to the output port and back to the Rx switch tree. As with the embodiment of FIG. 7, the Rx switch fabric 9200 carries both received back-scattered optical signals 9206 (dotted lines) as well as a test optical signals 9207 (solid line) on its waveguides 9205. As with the embodiment of FIG. 7, the test optical signals generated by the LiDAR transceiver 9051 are utilized for testing the switch fabric 9200 which otherwise would not be possible. It should be noted that the example arrangement 8000 depicted in FIG. 8 also applies to an arrangement of a laser and the LiDAR transceiver of the system of FIG. 9. The expected power to be measured at the power monitors 9400 of the upper tree does not match those of the lower tree during normal operation, however, if the switches 8024 and 8026 and power splitter 8022 are controlled to match those powers over a short monitoring duration, coordinate power monitor outputs from the two switch fabrics 9200 9300 may be combined and provided to commonreceivers RX. Such an architectural variation is shown in FIG. 9. It is to be noted as was in association with FIG. 7, that LiDAR systems with multiple transceivers 9051 and multiple separate Tx and Rx switch fabrics 9200 9300 may be run in parallel, in which case coordinate power monitoring outputs from the multiple switch fabrics may be combined and provided to common receivers RX. In some embodiments, a separate receiver RX is provided for each power monitor as in the embodiment of FIG. 7.

[0052] It is to be understood, that the component parts of the LiDAR system, may operate as part of a single instrument or device or may operate as part of a multiplicity of interconnected devices working together in proximity or remotely, or any combination thereof.

[0053] The above mentioned analysis of the switching patterns may be performed by a processing device 1080 7080 9080 such as a micro-processor / FPGA or any one or more other similar device, which may be implemented using one or more application specific integrated circuits (ASIC), micro-controllers, general purpose computer systems, digital signal processors, programmable logic devices (PLD), field programmable logic devices (FPLD), and the like, programmed according to the teachings as illustrated and described herein, as will be appreciated by those skilled in the optical, networking, software and computing arts.

[0054] In addition, two or more computing systems or devices may be substituted for any one of the processors or controllers described herein. Accordingly, principles and advantages of distributed processing, such as redundancy, replication, and the like, also can be implemented, as desired, to increase the robustness and performance of processors or controllers described herein.

[0055] The operation of the example beat frequency measurement methods may be performed by machine readable instructions. In these examples, the machine readable instructions comprise an algorithm for execution by: (a) a processor, (b) a controller, and / or (c) one or more other suitable processing device(s). The algorithm may be embodied in software stored on tangible media such as, for example, a flash memory, a CD-ROM, a floppy disk, a hard drive, a digital video (versatile) disk (DVD), or other memory devices, but persons of ordinary skill in the art will readily appreciate that the entire algorithm and / or parts thereof could alternatively be executed by a device other than a processor and / or embodied in firmware or dedicated hardware in a well- known manner (e.g., it may be implemented by an application specific integrated circuit (ASIC), a programmable logic device (PLD), a field programmable logic device (FPLD), discrete logic, etc.). For example, any or all of the component processes or steps of the beat frequencymeasurement methods could be implemented by software, hardware, and / or firmware. Also, some or all of the machine readable instructions represented may be implemented manually.

[0056] While particular implementations and applications of the present disclosure have been illustrated and described, it is to be understood that the present disclosure is not limited to the precise construction and compositions disclosed herein and that various modifications, changes, and variations can be apparent from the foregoing descriptions without departing from the spirit and scope of an invention as defined in the appended claims.

Claims

WHAT IS CLAIMED IS:

1. An integrated photonics system comprising: a plurality of pixels for launching and receiving optical signals into and from free-space; one or more switch fabrics coupled to said pixels and comprising a network of switches coupled via waveguides; at least one LiDAR transceiver coupled to the one or more switch fabrics for providing and receiving said optical signals from the plurality of pixels via the one or more switch fabrics; a plurality of power monitors optically coupled between the switch fabric and respective adjacent pixels; and processing circuitry configured for receiving digital data indicative of the power measured by the power monitors, for identifying a switching pattern of the one or more switch fabrics with use of the digital data and for determining a functionality of the one or more switch fabrics from the identified pattern.

2. The integrated photonics system of claim 1, wherein each power monitor of the plurality of power monitors comprises an optical tap for tapping a portion of the optical signal destined for the respective adjacent pixel, and a photodiode for converting the portion of the optical signal into an analog electrical signal.

3. The integrated photonics system of claim 2, wherein the plurality of power monitors are coupled to a plurality of receivers for converting the analog electrical signals into the digital data.

4. The integrated photonics system of claim 1, wherein the number of power monitors is less than the number of pixels.

5. The integrated photonics system of claim 3, wherein the number of receivers is less than the number of power monitors.

6. The integrated photonics system of claim 5, wherein the one or more switch fabrics comprises a plurality of switch fabrics driven by the same driving signals, and multiple coordinate power monitors are coupled to the same receiver.

7. The integrated photonics system of claim 6, wherein the number of power monitors is half the number of pixels, a power monitor coupled between each switch of a last level of a switch fabric of the one or more switch fabrics and one of the pixels the switch is coupled to.

8. The integrated photonics system of claim 1, wherein the processing circuitry is further configured for receiving reference digital data from the receivers indicative of a normal pattern of operation for the switch fabric, storing the reference digital data, and comparing the reference digital data with digital data received from the receivers for determining the functionality of the one or more switch fabrics.

9. The integrated photonics system of claim 8, wherein the processing circuitry is further configured for generating an alarm signal for indicating a failure of the one or more switch fabrics.

10. The integrated photonics system of claim 1 , wherein each of the one or more switch fabrics couples optical signals to and from the pixels for use in detection and ranging.

11. The integrated photonics systems of claim 1, wherein at least one of the switch fabrics of the one or more switch fabrics comprises a receive switch fabric and is coupled to pixels which are dedicated to receiving back-scattered LiDAR optical signals from free-space, and wherein the power measured by the power monitors includes a power of a test optical signal generated for monitoring a functionality of the receive switch fabric.

12. The integrated photonics systems of claim 1, wherein the one or more switch fabrics comprises a receive switch fabric and a transmit switch fabric both coupled to the same pixels, each pixel for launching and receiving optical signals into and from free-space, wherein the receive switch fabric directs a test optical signal to a first set of the power monitors adjacent the receive switch fabric, the test optical signal generated for monitoring a functionality of the receive switch fabric, and wherein the transmit switch fabric directs optical signals to a second set of power monitors adjacent the transmit switch fabric, the second set of power monitors separate and distinct from the first set of power monitors.

13. The integrated photonics systems of claim 12, further comprising a plurality of duplexers, one for each pixel, coupled to the pixel and to both the receive switch fabric and the transmit switch fabric, for transmission of optical signals from the transmit switch fabric to the pixel and transmission of back-scattered optical signals from the pixel to the receive switch fabric, and wherein the power monitors tap the optical power of optical signals travelling between the receive and transmit switch fabrics and the duplexers.

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